Lassig Bridge & Iron Works

Biography of The Lassig Bridge & Iron Works (1882-1900)

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Name Lassig Bridge & Iron Works
Preceded By Alden & Lassig (1881-1886)
Formed 1882, Independent in 1886
Defunct 1900
Succeeded by American Bridge Company
Key People Moritz Lassig (Owner)
Headquarters Chicago, Illinois
Railroads Served [Known Bridges] Burlington, Cedar Rapids & Northern Railroad [5]
Chicago & Alton Railroad [12]
Chicago & North Western Railway [83]
Chicago, Burlington & Quincy Railroad [11]
Chicago, Milwaukee & St. Paul Railway [32]
Chicago, Minneapolis, St. Paul & Omaha Railway [27]
Chicago, Rock Island & Pacific Railroad [37]
Great Northern Railroad [1]
Northern Pacific Railroad [5]
Toledo, Peoria & Western Railroad [3]
Union Pacific Railroad [7]
Shop Location Clybourn/Wrightwood Avenues

Lassig Bridge & Iron Works was originally founded by Moritz Lassig. Mr. Lassig was originally born in the Kingdom of Saxony in 1831. After studying at the Chemnitz University of Technology, he immigrated to the United States in 1851.
That fall, he accepted a position with Stone & Boomer, designing Howe Trusses. At this firm, it is believed that Lassig worked on portions of railroad and canals in Illinois. As a trusted assistant of L.B. Boomer, he continued to work at the firm until the American Civil War. During and after the Civil War, Lassig and Boomer worked together on the replacement several bridges that had been destroyed during war.
After the war, Lassig was hired as the General Superintendent at American Bridge Company of Chicago, where he spent approximately one year*. He left in 1871 when he opened his own shops at Clark and 16th Street in Chicago. These shops were soon purchased by the Chicago & Western Indiana Railroad to expand right-of-way.

*note: while some sources suggest Lassig spent only one year with American Bridge Company (of Chicago), his obituary suggests he stayed with the firm until 1876.

After this solo venture, Lassig partnered with John Alden, formerly of Leighton Bridge Works. The two reorganized Leighton into the Rochester Bridge Works, operating it for five years.
In 1882, Lassig began a solo venture at Clybourn and Wrightwood Avenues in Chicago. By 1886, Alden and Lassig agreed to go their separate ways, and Lassig focused his life on his own firm.
In the 1890s, Lassig Bridge & Iron Works was producing a considerable amount of steel, almost exclusively for railroad use. During the mid to late 1890s, most railroad bridges on the Chicago & North Western, the Milwaukee Road, the Omaha Road and the Rock Island were using Lassig products.
Lassig sold his work to the newly formed American Bridge Company in 1900, and ceased his involvement in bridge building. He died in Germany in January of 1902.
In the end, Lassig was perhaps the most prolific railroad bridge fabricator for the Midwestern United States. It has been widely reported that Lassig was always eager to evolve his bridge designs.

Double Intersection Warren Pony Truss

Typical Double Intersection Warren Pony Truss, constructed by Alden & Lassig. This span was built in 1883 at Des Plaines, Illinois and rebuilt for overpass use in 1910.

During the early Alden & Lassig years, lattice truss production continued based on Leighton designs. In addition, the Double Intersection Warren Pony Truss was perfected for railroad use, requiring less steel than a traditional Howe Truss. Many of these were replaced by the 1890s, but were rebuilt by Lassig for use as wagon overpasses.

Quadrangular Through Truss

Typical Quadrangular Through Truss with the C&NW/CMStP&O/CRI&P portals. Built 1892 in Sioux Falls, South Dakota

One of the most iconic designs is the Lassig Quadrangular Riveted Through Truss. Built for the Chicago & North Western Railway; the Chicago, Minneapolis, St. Paul & Omaha Railway; the Chicago, Rock Island & Pacific Railroad and the Union Pacific Railroad, these trusses made up a significant portion of all trusses built by Lassig.

Pratt Pony Truss
Typical Pratt Pony Truss, designed for the Chicago, Milwaukee & St. Paul Railway. Built 1899 at an unknown location.

In addition to the Quadrangular Truss, standard pin connected trusses were built for the Chicago, Burlington & Quincy Railroad as well as the Chicago, Milwaukee & St. Paul Railway.
American Bridge Company phased out the Lassig name by 1902, but production at the Chicago plant remained until 1928. The buildings remained until the late 1980s, when they were demolished for redevelopment. The land is now occupied by several commercial buildings.
Today, Lassig bridges can still be seen throughout the Midwest. Many of the early grade separations in Chicago, as well as mainlines for ex C&NW lines in particular remain nearly exclusively Lassig products.
The author has added counts of bridges built for each railroad, based on Bridgehunter.com reports from March 2021. It is worth noting there is almost certainly uncounted spans for every railroad, and some spans may be double counted due to relocations of various spans. The goal of this count is to demonstrate how widely used Lassig products were, and how certain railroads purchased Lassig products exclusively.

Howe Pony Truss
An unusual Riveted Pony Truss, built 1898 for the Chicago, Minneapolis, St. Paul & Omaha at Fall Creek; Wisconsin. This appears to be an experimental design.

A sample of plaques and projects completed by Lassig Bridge & Iron Works can be seen below. Unlike many builders, Lassig had little change in the plaque design or format during their 18 year run.
Early plaques featured a shield shaped design with decorative features and said "M. Lassig, Builder". Plaques after 1889 appear to use a standard rectangle shape with rounded indented edges, with text saying "Built by the Lassig Bridge and Iron Works Chicago Ill".
The plaque shape remained for at least two years after American Bridge took over, although these plaques stated "Built by American Bridge Company, Lassig Branch".
By analyzing the mounting hole size and shapes on the plaques, one can learn a great deal about the age of said bridge. It appears that the pre-1889 plaques had two small bolts, located in the upper corners. The 1889-1896 plaques had two larger bolts, located midway on the sides. The post-1896 plaques seem to have had a single bolt, located upper center on the plaque. 1896 seems to be the only year of overlap of these styles.

American Bridge Company plaque Post-1950 Design

An excellent condition plaque from 1890. Seen on an underpass in Omaha, Nebraska.

American Bridge Company plaque 1910-World War II Design

Typical pre-1889 plaque, showing the details and shape. Seen on a bridge in Marsailles, Illinois.

American Bridge Company plaque 1910-World War II Design

Late plaque from 1899 showing the top-center mount hole. Seen on a bridge in Adel, Iowa.

American Bridge Company plaque 1900-1910 Design

Typical pre-1896 plaque with side mounting holes. Seen on a bridge in Sioux Falls, South Dakota

American Bridge Company plaque Alternate Design

A typical plaque, showing little changes before the American Bridge Company takeover. Seen on a bridge in Ames, Iowa.

American Bridge Company plaque from Lassig branch

An American Bridge Company plaque, produced at the Lassig Branch in 1901. This design was phased out prior to 1902. Seen on a bridge in Murray, Iowa.

Selected Works
Louisiana Rail Bridge
Nelson Rail Bridge
North Sioux City Rail Bridge


Source Type


Company History Obituary of Moritz Lassig

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